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Hydraulic Punching and Shearing' Machines.       291

At Fig. 284 is shewn an Hydraulic Punching and
Shearing Machine, designed by the late Mr. R. H. Tweddell, of
Westminster, for performing the same operations as the foregoing
by means of water pressure. In this example there is no reason
why the three parts should be combined except to save floor space.
A cylinder and ram are required for each operation : A for punch-                        I

ing, B for angle-cutting, and c for shearing; there are also the                        J

lifting pistons at I) D D. Water being supplied from the accumu-
lator pumps at a pressure of 1500 or 2000 Ibs. per sq. inch,
two pipes are connected with each cylinder, one for ' pressure'
and the other for ' exhaust,7 marked P and E respectively. The
valve boxes at F are supplied with piston valves (worked from
hand and foot levers j and K) to control the supply and exhaust;
but a constant pressure, on the pistons D D, causes the rams to
rise when water is exhausted from the main cylinder. A
small lever G, moved by ram c when at the end of its down                        f

stroke, is connected to a screwed rod H, having adjustable discs,
which restore the levers j nd K to the horizontal position,
stopping the water supply and the movement of ram c : this is
known as cut-off gear. Two overhanging cranes L, L? support
the plates while being operated on.

The Multiple Punching or Shearing Machine in
Fig. 284^, on Tweddell's system, has been designed to prepare
plates required in forming wrought-iron pipes for conveying
water or oil across country, and known as 'pipe lines;' it is also
useful for ships' funnels and masts, and for girder work generally.
A shearing blade or row of punches can be attached at will; the
latter being shewn in operation at A. The punches are set alter-
nately low and high, so that th^ punching resistance commences
gradually, and they are attached to a beam B capable of vertical
movement Downward motion is obtained by a ]bl!ward travel
of bar c, whose lower rollers press upon beam B, while the upper
ones re-act upon inclined planes D, D, b, fastened to the framing,
The working ram E (see enlarged section) moves bar c; water
entering the cylinder F from behind, and connection between
c and E being made with a toggle o, to allow for vertical travel,
K is the valve boic with piston-valve moved by lever j, and the
cut-off is effected automatically by the bell crank K, as